if you have a top mount you have the benifit of about 6-9 feet less turbo piping. but when you have an intercooler above your engine at absorbs heat much easier, as hot air tends to rise above right into it. there is always a trade off. i went with a front mount for one reason only. its a front mount intercooler and it looks mean as hell.

 

Front mounts are also larger than top mounts (for the most part) and are in a better location to take in air. Therefore, they make more power but lag the turbo more.

 

Don't think about placement when you want to find a good intercooler.

You have to consider only the follwing 2 things:

1. Efficiency (% of temp drop from when it entered the IC to when it left the IC)

2. Pressure drop (how much more does the turbo has to "work" to "bring" the same pressure to the combustion chamber).

Typically, FMIC has a greater pressure drom than the top mounts. However, pipe lengh and general "volume" is not the only thing that can affect that. Poor inter design can increase the pressure drop. End tank design, core design, diffuser plates (if any) can contribute to either pressure drop increase or decrease.

At the same time, FMIC usually offer greated efficiency, due to their size. But then again, core and end tank design can also screw up the efficiency.

So to answer your question, you need to find an IC with minimal pressure drop and max efficiency and FMICs, TMICs and SMICs offer different combinations of those factors.

With a small turbo, pressure drop is very important as smaller turbos fall out of their efficiency zone if they have to work harder. In other words, to have the car "run" 16psi, it would have to have ~ 19psi at the turbo.

Also, smaller turbos create hotter charge than larger turbos.

If you have a smaller turbo (IHI based), IC choice is critical, as you can get an IC and actually loose HP.

If you have a larger turbo (garret or large Mitsu's), FMIC is typically the right thing to do.

Thast why it is all about tuning. By tuning, I don't mean fuel/spark deal. I am talking about complete car tuning which involves selecting the right parts for the job rather than just grab whats available.

Hope this helps.

- Alex

 

this is going to be a debate for a long time i think. with all the new larger top mounts coming out these days (aps, turbo xs, vishnu) it makes the decision a little harder for some people. i think the easiest way to make a decision would be to make a list of pro/cons for both and then decide what YOU want out of the intercooler.

 

Once again, you make a mistake bringing "big" into the converstation. Bigger doesn't mean better. It is all about the design of the end tanks, internal diffusers and core characteristics. On top of that, you need to consider the other mods on the car. Only then one can make an educated "guess" of what is best.

At the same time, I am not going to fool myself and say that anyone can get all the data on the available intercoolers. While some companies use "Bigger=Better" strategy, others use other factors. But then again, most intercoolers from Australia come from the same manufacturer and sometimes two companies will market identical intercooler which are only differ in their brand label in different ways.

- Alex

 

what intercooler are you running alex?

 

that's what i heard, that the liquid to air ic wasn't a good idea. anyone care to speculate why?

 

I am running TRUST Spec-R FMIC with my T67.

andyas, HyperFlow makes IC's for more than enough AU companies. Of course, not ALL of them, but enough. And, they even brand it as their own as well.

- Alex

 

Another thing to keep in mind that really big top-mount ICs act as really big heat-sinks if parts of the core aren't covered by the rubber duct/seal. With portions of the IC core not getting cooled by ducted ambient air, average temp drop/IC inefficiency takes a big hit in the real world. A hit that goes unseen during open-hood dyno tested where air fans and cool-down periods are used to keep temps in check. Good IC design is a careful game of give and take. It's just really important to know what your priorities are when designing and/or choosing an intercooler. The "bigger-is-better" game is best left for marketing folks who feel that real performance comes secondary to phat looks and gee-whiz factor

Just my 2c,
shiv
________
STRAWBERRY COUGH

 

Unless of course you modify your stock air duct/diverter to direct air over EVERY part of your "bigger" TMIC . But yes I fully agree with the advantages of ducting/forcing the air over the TMIC and every last part of the TMIC. I was looking into the STi TMIC for that very reason; you can get the STi rubber/seal/duct that forces air over ALL parts of the intercooler.

But in the end I HAD to go with the TXS TMIC becuase of price and VERY low pressure drop across the intercooler. I need ALL the help I can get getting 19-20psi out of a VF series turbo at 6000ft above sea level [heh]. But I honestly do like a lot of the designs of TMIC out there... I didn't really succomd to the "bigger is better" philosophy, like I mentioned I needed a TMIC with the lowest pressure drop across it = TXS TMIC at the time.